RE: plans for single-precision support?

[Tim Rueth]

> -----Original Message-----
> From: Tatsuro MATSUOKA [mailto:address@hidden 
> Sent: Tuesday, August 31, 2010 9:40 PM
> To: address@hidden; 'Martin Helm'; address@hidden
> Subject: RE: plans for single-precision support?
> 
> Hello
> 
> It seems that octave-3.2.3/MinGW32 supports the 'single' function.
> 
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> warning: mark_as_command is obsolete and will be removed from 
> a future version of Octave 
> octave-3.2.3.exe:1:C:\Programs\Octave\3.2.3_gcc4.4.0\bin
> > help single
> `single' is a built-in function
> 
>  -- Built-in Function:  single (X)
>      Convert X to single precision type.
> 
>      See also: double
> 
> 
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> octave-3.2.3.exe:11:C:\Programs\Octave\3.2.3_gcc4.4.0\bin
> > x=0.1
> x =  0.100000000000000
> octave-3.2.3.exe:12:C:\Programs\Octave\3.2.3_gcc4.4.0\bin
> > y=single(x)
> y =  0.100000001490116
> octave-3.2.3.exe:13:C:\Programs\Octave\3.2.3_gcc4.4.0\bin
> > whos
> Variables in the current scope:
> 
>   Attr Name        Size                     Bytes  Class
>   ==== ====        ====                     =====  =====
>        x           1x1                          8  double
>        y           1x1                          4  single
> 
> Total is 2 elements using 12 bytes
> 
> **********************************************************************
> 
> If you want to install octave-3.2.4/mingw32, please read 
> carefully the below, (The oct2mat issue should be treated in 
> case installing the whole octave-forge package.)
> 
> http://wiki.octave.org/wiki.pl?OctaveForWindows
> 
> Regards
> 
> Tatsuro
> 
> --- Tim Rueth wrote:
> 
> > Oh, I'm still running 3.2.3 (Vista).  I should upgrade to 
> 3.2.4 then.  
> > I'm running into memory problems, and I'm hoping that if I 
> change some 
> > of my matrices from double to single I can cut the memory 
> requirements way down.
> > 
> > --Tim
> >  
> > 
> > > -----Original Message-----
> > > From: Martin Helm [mailto:address@hidden
> > > Sent: Tuesday, August 31, 2010 3:20 PM
> > > To: address@hidden; address@hidden
> > > Subject: Re: plans for single-precision support?
> > > 
> > > Am Dienstag, 31. August 2010, 23:26:47 schrieb Tim Rueth:
> > > > Does anyone know when single-precision data types, 
> i.e., single(), 
> > > > will be supported?
> > > > 
> > > > --Tim
> > > 
> > > Maybe I do not understand your question, single() is available in 
> > > octave 3.2.4.

Oh, you're right.  I read in the Octave Manual for single() that:

        Note: this function currently returns its argument converted to
double precision
        because Octave does not yet have a single-precision numeric data
type.

But I tried your test case and sure enough, it works, thanks.

Since it appears Octave defaults to double, I'm still having to initially
allocate memory for twice the space that I need, then I give back half.  I'm
using ndgrid() to create numerous very large matrices.  Is there a way to
invoke ndgrid() so that it just creates single-precision matrices without
recasting them from double back to single?

Thanks,

--Tim